Steam turbine vehiclepart and power plant location

[chaosvolt]

Summary

SUMMARY: Content "Add high-power steam turbine engine, small power plant overmap special as a special spawn"

Purpose of change

An additional thing I had in mind, with the goal of adding a high-tier engine option for steam engines, which are generaly fairly rare outside of the underwhelming craftable version.

Describe the solution

• Added item definition for steam turbine part. Its listed horsepower is based on what seemed like a good middle-ground value given steam turbines have a fairly massive range of power outputs, and I figured this would make sense for a value that's significantly above the other steam engines while being about half the value of the smallest gas turbine. Its sheer bulk meanwhile was derived via a rough estimate of the difference in size between the V12 gasoline engine and the small gas turbine, as applied to the size of the medium steam engine. Also fits steam turbine engines, especially for power plants, generally being pretty big.
• Added vehiclepart definition for steam turbine. Efficiency is based off how gas turbine engines have 5% lower efficiency than regular gasoline engines, as applied to the efficiency rating of normal steam engines. This also helps differentiate it better from the heavier diesel engines, as making the efficiency scale down more would put its power stats a lot closer to that of the V12 diesel engine. Also gains the benefit added to turbine engines and giant motors.
• Added a furniture definition that can be deconstructed to obtain a steam turbine. This is planned to see use in the new power plant location, as detailed below.
• Add the mapgen files for power plant. Front half has a parking lot and the main office/workshop build, partially modeled after the sewage treatment plant's design. The back half has fuel storage/processing, the main turbine and generator, and finally a small amount of electrical substation equipment. The southwest corner has variations depending on type of fuel, with coal, natural gas (with chance of a burning gas leak), petroleum, and geothermal (based of speculative proposals to test injection well geothermal methods in New England, also with a chance of some seismic activity disrupting the surface) as potential options.
• Added mapgen chunks for chance of something having gone wrong in two of the power plant variants.
• Add mapgen palette for power plant (basically done aside from item mapping).
• Added overmap terrain entries for power plant location.
• Add overmap special for power plant.
• Found places to fit steam turbine furniture into the shipwreck and Aftershock's municipal reactor.

Describe alternatives you've considered

Adding pipe terrain/furniture specifically for implying pumping of natural gas and/or petroleum. Right now sewage pipes are used as a standin for that, something also done in locations like the private airport.

Nuclear power plants, solar farms, and wind farms likely would make more sense as separate overmap specials since the floorplan will vary too much for a single corner to cover it, plus logically we could mainline Aftershock's nuclear plants in the process.

Testing

Checked affected files for syntax and lint errors. More testing to follow as implementation progresses.

Worth noting: the other steam engines yield filled bottles of water when smashed, hence this was omitted from the bash results of the steam turbine vehicepart for now.

Additional context

[scarf005]

destroying 750hp steam turbine

shipwreck

small power plant

aftershock municipal reactor